1. Field of the Invention
The present invention relates to a wire holder and also relates to an optical fiber connector, for example, for securing an optical fiber to a case by pressing an optical fiber inserted in the case by a holder. The present invention enables an optical fiber or other wire to be easily and reliably secured by using the pressing force from the optical fiber and using a position away from a holding piece receiving the pressing force as a supporting point for displacement of the holding pieces to press against the optical fiber.
2. Description of the Related Art
Conventionally, the optical fiber used for optical communication apparatuses has been comprised of a wire-like core cable comprised of a core formed in a circular cross-sectional shape or a core and cladding and of a jacket covering the core cable so as to enable various types of light to be transmitted by the core cable. Therefore, the core cable has been formed by optical glass or a plastic. Further, the jacket has been formed by urethane, polyethylene, vinyl, or other plastic.
As opposed to this, the optical fiber connector positions and holds the core cable through the jacket. The light emitted from the end face of the core cable is fired into an optical communications apparatus or another optical cable. For example, as shown in FIG. 20, the optical fiber connector 1 disclosed in Japanese Examined Utility Model Publication (Kokoku) No. 8-2643 inserts an optical fiber 2 into a plug 3 for positioning, then secures and holds the optical fiber 2 by a holding fitting 4.
That is, a through hole is formed from the rear end face of the plug 3 toward the front end. The front end side is formed so as to project out in a tubular shape along the through hole. The optical fiber 2 is stripped of its covering 2a in advance by a predetermined tool to expose the core cable 2b at the front end. In this state, it is inserted in the through hole of the plug 3. Due to this, the optical fiber connector 1 guides the optical fiber 2 by the through hole and positions the optical fiber 2.
The holding fitting 4 is formed by processing, for example, a metallic material into a U-shaped cross-section having the U-shaped grooves 4a and 4b at the front ends. This holding fitting 4 is inserted from the opening 3a of the plug 3 and pressed so that the optical fiber 2 is sandwiched by the U-shaped grooves 4a and 4b. The U-shaped grooves 4a and 4b thereby grip the optical fiber 2 from the outer side of the covering 2a. Due to this, the holding fitting 4 holds the optical fiber 2 at the plug 3 and prevents detachment of the optical fiber 2 from the through hole or rattling of the optical fiber 2.
In the optical fiber connector 1, by securing the optical fiber 2 in this way, it is made possible to connect to various apparatuses etc. by the pawl 3b formed at the side surface of the plug 3.
In this type of optical fiber connector, however, if the force holding the optical fiber 2 is weak, when a large force pulls upon the optical fiber 2, the optical fiber 2 will detach from the optical fiber connector.
In the optical fiber connector 1 shown in FIG. 20, the widths of the U-shaped grooves 4a and 4b may be made narrower to increase the force gripping the optical fiber 2 and, due to this, to increase the force holding the optical fiber 2. Further, it is also possible increase the number of the U-shaped grooves so as to increase the force holding the optical fiber 2.
If the force holding the optical fiber 2 is increased in this way, however, the stress acting on the core cable 2b also increases and the birefringence of the light in the core-cable 2b will increase by that much and the quality of transmission of the light will become impaired. Further, when the holding fitting 4 is inserted in the plug 3, it is necessary to press it by a large pressing force. Due to this, it becomes difficult to easily assemble the optical fiber connector 1.
Due to this, in the optical fiber connector 1 of the configuration shown in FIG. 20, in practice, there is the defect that it is difficult to increase the force holding the optical fiber 2 and there is the problem that it becomes difficult to reliably secure the optical fiber 2 by that amount.
As a method for solving these problems, the method of holding the optical fiber 2 by an adhesive etc. instead of the holding fitting 4 may be considered. Further, in the optical fiber connector of the configuration of FIG. 20, the method of increasing the holding force by post-processing may also be considered. In the case of these methods, however, there is the problem that it becomes difficult to easily connect the optical fiber 2 to the optical fiber connector.